public-key encryption

(PKE, Or "public-key cryptography") An
encryption scheme, introduced by Diffie and Hellman in 1976,
where each person gets a pair of keys, called the public key
and the private key. Each person's public key is published
while the private key is kept secret. Messages are encrypted
using the intended recipient's public key and can only be
decrypted using his private key. This is often used in
conjunction with a digital signature.

The need for sender and receiver to share secret information
(keys) via some secure channel is eliminated: all
communications involve only public keys, and no private key is
ever transmitted or shared.